During the Alliance-Horde War, he and his friend Verdrak were nearly killed by their own kind until they were later saved by Malgar just before their execution. He then aided the Garad'kra, telling them about Aratas and an imprisoned group of orcs. While travelling to Desolace by a Zeppelin, Dorthar underwent a series of tests. When the group arrived to Maraudon, Dorthar promised to free and accompany the prisoners to the safety while the rest of Garad'kra fought against Aratas and killed him. After that, Dorthar was the first centaur to join the Horde.